1. Field of the Invention
Devices, systems, and methods consistent with the invention relate to an internal combustion engine capable of running on multiple types of fuel.
2. Description of the Related Art
Over the last century, the use of internal combustion engines for power and propulsion has become almost universal. The vast majority of today's internal combustion engines are designed to burn gasoline using a four-stroke Otto cycle. As shown in FIGS. 1A-1D, the four steps (or strokes) of this cycle are the: (1) intake stroke (FIG. 1A), where an air/fuel mixture 10 is drawn into the cylinder 20 through an intake valve 30 by the downward movement of piston 40; (2) compression stroke (FIG. 1B), where the air/fuel mixture 10 is compressed by the upward movement of piston 40; (3) power stroke (FIG. 1C), where the air/fuel mixture 10 is ignited by a spark plug 50, and the resulting combustion of the air/fuel mixture 10 (combustion products 12) pushes the piston 40 downward; and (4) exhaust stroke (FIG. 1D), where the upward movement of piston 40 expels the combustion products 12 through an exhaust valve 60.
Today, however, there is increasing pressure to move away from gasoline as a fuel, due to such factors as its relatively high refining cost and deleterious combustion byproducts. Many other types of fuels are therefore competing for supremacy in the marketplace, such as conventional Diesel, Bio-Diesel, Hydrogen, Methane, Liquefied Petroleum Gas (LPG), Liquefied Natural Gas (LNG), ethanol, and methanol. Each can be burned in reciprocating engines with various degrees of efficiency, emissions and source reliability. However, each fuel varies widely in its combustion properties—therefore requiring that an engine utilizing each particular fuel have particular compression, fuel introduction, and ignition parameters. In view of these differences, current technology dictates that different engine designs be optimized and used for each fuel type.
Such narrow operability is inconvenient and inefficient, as end users might desire to utilize whatever fuel is available, or whatever fuel is cheapest. Further, it is highly likely that there will be fragmentation of fuel use across national boundaries, as some countries adopt different strategies for their future fuel needs. Accordingly, there exists a need to provide engines for power and propulsion that can run on a multitude of fuel types, and traverse a wide variety of infrastructures seamlessly.